What is the underlying cause of severe ascites and subsequent small bowel obstruction (SBO) two years later in a patient after egg retrieval surgery?

Underlying Cause: Post-Egg Retrieval Adhesive Small Bowel Obstruction

The most likely underlying cause is peritoneal adhesions that formed after the egg retrieval surgery, which initially manifested as severe ascites and subsequently led to adhesive small bowel obstruction two years later.

Pathophysiologic Mechanism

The clinical sequence you describe follows a well-established pattern of adhesion formation after peritoneal injury:

• Egg retrieval is an intra-abdominal procedure that can cause peritoneal inflammation and injury, triggering the adhesion formation cascade 1
• Severe ascites immediately post-procedure represents reactive ascitic fluid (rA) formation in response to peritoneal inflammation, which activates mesothelial cells to initiate adhesion formation 2
• The two-year interval to SBO is consistent with the natural history of adhesive disease, as adhesions can cause obstruction months to years after the initial peritoneal insult 1

Why Adhesions Are the Primary Culprit

Even in patients with "virgin abdomen" (no prior major abdominal surgery), adhesions remain the dominant cause of small bowel obstruction:

• Adhesions account for 26-100% of SBO cases in virgin abdomen patients, with most studies showing 47.9% overall 1, 3
• Band adhesions are particularly common in virgin abdomen SBO (65% of cases), as opposed to matted adhesions which predominate after major surgery 1, 3
• Congenital adhesions can exist as anomalous intra-peritoneal bands from embryologic remnants, but acquired adhesions from any peritoneal injury (including minimally invasive procedures) are more likely 1

Alternative Etiologies to Consider (Less Likely)

While adhesions are most probable, other causes must be excluded:

• Malignancy accounts for only 4-13% of virgin abdomen SBO, making it less likely but still requiring evaluation 1, 3
• Internal hernias, Meckel's diverticulum, or other congenital bands are possible but statistically less common 1, 3
• The severe ascites at initial presentation argues against malignancy as the primary cause, since malignant ascites typically develops gradually rather than acutely post-procedure 1

Clinical Implications for This Patient

The reactive ascites was likely the body's inflammatory response to peritoneal injury during egg retrieval, with proteins in the ascitic fluid activating mesothelial cells to form fibrous adhesions over subsequent weeks to months 2:

• Peritoneal inflammation from the procedure caused formation of reactive ascitic fluid 2
• This fluid activated peritoneal mesothelial cells to secrete extracellular matrix and form adhesive bands 2
• Over two years, these adhesions matured and eventually caused mechanical bowel obstruction 1

Diagnostic Confirmation

CT scan with IV contrast should have been performed to confirm the diagnosis and exclude other causes:

• CT has 76% accuracy for determining SBO etiology compared to operative findings 3
• CT can identify transition points, closed-loop obstructions, and signs of ischemia requiring urgent surgery 1
• In virgin abdomen patients, CT helps exclude malignancy (present in 4-13% of cases) and other non-adhesive causes 1, 3

Important Caveat

Even at surgical exploration, 6-40% of virgin abdomen SBO cases have negative findings (no identifiable cause), which can be frustrating but is well-documented 1, 3. However, given the temporal relationship to egg retrieval and initial severe ascites, adhesive disease remains the most plausible explanation in this case.